Fluorescent panel lamp structure



2 Sheets-Sheet l R. F. HOLLE FLUORESGENT PANEL LAMP STRUCTURE May 24, 1966 Filed Aug. l5, 1962 /Z/-ff/JJ" Irwehfbs: RObeT-fl': .I-IOLL@ b9 HIS ACL' 0171629 May 24, 1966 R. F. HOLLE 3,253,175

FLUORESCENT PANEL LAMP STRUCTURE Filed Aug. l5, 1962 2 Sheets-Sheet 2 lm/emft-ov: Robefl fr HOLL@ b5 J His Aflflfovneg United States Patent O 3,253,175 FLUORESCENT PANEL LAMP STRUCTURE Robert F. Holle, Lyndhurst, Ohio, assignor to General Electric Company, a corporation of New York Filed Aug. 15, 1962, Ser. No. 217,003 Claims. (Cl. 313-192) This invention relates to fluorescent panel lamps and, in particular, to a fluorescent panel lamp structure which may be used to achieve multiple illumination levels 0r to produce more light in a given size of lamp.

Fluorescent panel lamps are discharge lamps which operate on the same principle as the common elongated fluorescent lamp. However, in the panel lamp, the discharge occurs in a labyrinthine channel permitting a relatively long discharge in a small area; thus it provides an area light source as opposed to the line source of the elongated fluorescent lamp. Additional advantages of the panel lamp lie .in its compact nature and greater ease of handling. These improved panel lamps and the methods for making them are described and claimed in copending application Serial No. 106,829, led May 1, 1961, by Richard S. Christy, entitled Panel Lamp and Manufacture Thereof, and assigned to the same assignee as the present invention.

Incandescent lamps which permit selective energization of filaments to obtain varying levels of light output are commercially available. It is often desirable to have -corresponding flexibility in controlling the light level of fluorescent lamps.

The general `object of the invention is to provide an improved fluorescent panel lamp providing more light from a given size or allowing selective control of the electrical discharge path to vary the light level.

A more specific object is to provide a fluorescent panel lamp which permits multiple levels of light output therefrom while maintaining uniformity of radiation over the exposed surface of the lamp.

Another object is to provide a structure which enables the discharge arc length to be substantially doubled without substantially increasing the surface area.

In accordance with the illustrated embodiment of the invention, a fluorescent discharge envelope is formed by sealing two molded vitreous plates and a coextensive partition plate together along their margins, the partition plate ibeing interposed between the molded vitreous plates. Labyrinthine channels through which the electrical discharge extends are formed in the molded vitreous plates, the walls of the channels abutting the partition plate. An electrode is mounted at one end of each channel and an aperture is formed at a point in the partition plate to interconnect the other ends of the labyrinthine channels on either side of the partition plate. The effective length of the discharge path in a lamp of a given size or varea is thereby doubled. An additional electrode may be mounted adjacent the aperture in the partition plate and selective energization of the electrodes then permits control of the electrical discharge path and the resulting illumination level.

For other features and for a better understanding of the advantages of the invention, attention is now directed to the following detailed description of specific embodiments and to the accompanying drawings. The features of the invention believed to be novel will be more particularly pointed out in the appended claims.

In the drawings:

FIG. 1 is a plan View of a rectangular fluorescent panel lamp embodying the invention.

FIG. 2 is a side sectional View of the lamp of FIG. l.

FIG. 3 is a plan view of a round fluorescent panel lamp embodying the invention.

3,253,175 Patented May 24, 1966 ICC FIG. 4 is a partially sectioned side View `of the round fluorescent panel lamp of FIG. 3.

Referring to the drawings and more particularly to FIGS. l and 2, the illustrated rectangular fluorescent panel lamp is formed of two identical molded plates 5 and 6, which together form the envelope of the fluorescent panel lamp. A partition plate 8 is interposed .between the molded glass plates 5 and 6, partition plate 8 being coextensive with plates 5 and 6. Molded plates 5 and 6 and partition plate 8 may be formed of glass or other suitable material. The margins of the molded glass plates 5 and 6 and of the partition plate 8 are hermetically sealed together to form a marginal ledge 10 extending around the four sides of the panel lamp. The sealing is preferably done by heating the glass above its strain point but not to softening temperature and applying a very high pressure to the margins to cause lateral flow of glass with formation of a rounded fillet at the internal juncture of the surfaces, following the teachings of copending application Serial No. 106,829, led May l, 1961, of Richard S. Christy, entitled Panel Lamp and Manufacture Thereof, and `assigned to the same assignee as the present invention.

Each of the glass plates 5 and 6 is molded into six parallel grooved sectionsror channels 12 extending side by side and joined together by short sections 13 where the lengthwise partitions or walls 14 end, thereby forming continuous labyrinthine channels on either side of partition plate v8. The salient portions of the partitions or Walls 14 abut the partition plate 8, the surfaces being pressed together into close conformance but not sealed or fused together. Providing there is close conformance of the surfaces along the junctures of wall 14 and partition plate 8, the electric discharge will not leak through and short circuit but will follow the labyrinthine channel through from end to end.

In accordance with the invention, an aperture 17 is provided in the partition plate 8, located preferably at a corner and corresponding to ends of the respective labyrinthine channels on either side of partition plate 8. Main discharge supporting electrodes 20 and 21 are provided in each labyrinthine channel at the ends of the labyrinthine channels remote from the aperture 17 in partition plate 8, main electrode 20 being supported within the labyrinthine channel formed by molded glass plate 5 while main electrode 21 is supported within the labyrinthine channel formed by molded glass plate 6. An auxiliary discharge supporting electrode 22 is mounted adjacent aperture 17 in partition plate 8, auxiliary electrode 22 being supported within the labyrinthine channel formed by molded glass plate 5. Each of the main and auxiliary discharge supporting electrodes consists of a tungsten filament coated with activating material and is supported by inleads 25 sealed through the marginal ledge The interior surfaces of molded glass plates 5 and 6 are coated with a phosphor, indicated at 27, 28 which is excited by the 2537 Angstrom radiation resulting from the discharge through the mercury vapor to produce visible light. The partition plate may be coated on each surface with `a phosphor indicated at 29 so as to obtain maximum generation of visible` radition. Alternatively, a coating reflective to ultraviolet radiation may be applied. The lamp is provided with the usual ionizable lilling consisting of mercury and an inert starting gas such as argon at a pressure of a few millimeters of mercury.

The fluorescent panel lamp structure of the invention provides multiple levels of light output upon selective application of energizing potentials to main discharge supporting electrodes 20 and 21 and auxiliary discharge supporting electrode 22. In operation, application of voltage between main electrode 20 and auxiliary electrode 22 will result in the usual electrical discharge therebetween through the upper half of the lamp. Similarly, application of voltage between main electrode 21 and auxiliary electrode 22 will result in the usual electrical discharge through the lower half of the lamp, the discharge reaching auxiliary electrode 22 through aperture 17 in partition plate 8. A third mode of operation is effected by Vapplication of voltage between main electrodes and 21. In this instance, the electrical discharge will traverse both labyrinthine channels via aperture 17 in partition plate 8 to produce visible light radiation from both surfaces of the lamp. In this mode of operation, the arc length is effectively doubled. If desired, the auxiliary electrode may be used at starting only in order to lower the overall voltage needed to start the discharge, .and not used during operation in order to increase efiiciency by eliminating the cathode voltage drop thereat.

In use, the fluorescent panel lamp of the invention may be suspended an appropriate distance from a ceiling with the plane of the lamp parallel to the surface of the ceiling.

Production of an electrical discharge through .that portion of the lamp facing the ceiling surface would produce an indirect lighting effect in the surrounding area by virtue of refiection of the emitted light from the ceiling surface. On the other hand, establishment of an electrical discharge through that portion of the fiuorescent panel lamp of the invention facing the floor would be productive of a direct lighting effect on the surrounding area. If an electrical discharge is established .through both portions of the lamp both direct and indirect lighting effects are obtained. Thus, the fiuorescent panel lamp structure of the invention provides three modes of operation to produce three levels of illumination.

The uorescent panel lamp structure of the invention may also be used in a round fluorescent panel lamp, as illustrated in FIGS. 3 and 4. The construction of the round fluorescent panel lamp is generally similar to that of the previously described rectangular panel lamp, the sections or channels which comprise the labyrinthine channels being concentric rather than parallel as in .the rectangular panel lamp. The envelope of the .round panel lamp is formed of two circular or disk-like molded vplates 30 and 31 with a partition plate 32, coextensive with plates 30 and 31, interposed therebetween. Molded plates 30 and 31 and partition plate 32 may be formed of glass or other suitable material. Molded plates 30 and 31 and partition plate 32 have circular holes in their centers and are sealed together at their inner and outer margins to form marginal ledges 34 and 35 respectively. The glass plates 30 and 31 are molded to define, in cooperation with the partition plate 32, labyrinthine discharge channels 37 by virtue of the abutment of the salient portions of concentric walls 40 with the surfaces of partition plate 32. The -concentric channels, which comprise the labyrinthine channels, are joined together by short sections 41 which are not traversed by the concentric walls 40. An internal partition or Wall 43 extends partially across the concentric channels on one side and wholly .across the concentric channels on the diametrically opposite side and causes the electrical discharge to curve around the ends of the concentric Walls 40. The labyrinthine discharge channels on either side of partition plate 32 thus comprise a pair of reverting concentric 4semicircular portions on each side of interior wall 43 interconnected by a full circular portion.

In accordance With the invention, an aperture 45 is formed in partition plate 32 adjacent corresponding ends of the labyrinthine channels disposed on opposite sides of partition plate 32.

Main discharge supporting electrodes 46 and 47 are disposed on opposite sides of partition plate 32 at the ends of labyrinthine channels remote from aperture 45. Only electrode 46 is visible in FIG. 3 because the other electrode 47 is disposed directly beneath it under parti- .tion plate 32, Auxiliary discharge supporting electrode 48 is positioned adjacent aperture 45 within the channel formed between molded glass plate 30 and partition plate 32. Each of the main and auxiliary electrodes consist of a tungsten filament coated With activating material and is supported by inleads 49 sealed through the interior marginal ledge 34.

The interior surfaces of the molded glass plates 30 and 31 and of partition plate 32 are coated with an appropriate phosphor as indicated at 50, 51 and 52. An ionizable filling and inert starting gas are introduced into the labyrinthine channels, the aperture 45 enabling an electric discharge to pass between the respective labyrinthine channels. Operation of the round fluorescent panel lamp embodiment of the invention is similar to that of the previously described rectangular embodiment. Visible light is emitted from molded glass plate 30 upon establishment of an electric discharge between main discharge supporting electrode 46 and auxiliary electrode 48 while light emission from molded glass plate 31 is obtained by application of appropriate potentials to main electrode 47 and auxiliary electrode 48 to establish an electric discharge therebetween. As in the rectangular embodiment, light emission from both glass plates or surfaces of the envelope is obtained by application of suitable potentials to both main electrodes to establish an arc which ltraverses both labyrinthine channels via aperture 45. In the latter mode of operation the length of the electrical discharge is doubled. Thus, the round fluorescent panel lamp embodiment also provides three levels of illumination.

The specific embodiments of the invention which have been illustrated and described in detail are intended by way of example only and modifications will readily occur to those skilled in the art. It is intended by the appended claims to cover any such modifications as fall within the true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A iiuor-escent panel lamp for producing multiple illumination levels comprising:

(a) an envelope formed by a first vitreous plate and a second vitreous plate,

(b) a partition plate coextensive with and interposed between said first and said second vitreous plates and having an aperture formed therein, said first and said second vitreous plates and said partition plate being sea-led together along their margins,

(c) a plurality of vitreous walls extending from said first and said second vitreous plates and abutting said partition plate to form labyrinthine discharge channels within said envelope on either side of said partition plate,

(d) a first electrode mounted in one of the labyrinthine discharge channels in a region remote from said aperture,

(e) a second electrode mounted in the other labyrinthine discharge channel in a region remote from said aperture, and

(f) a third electrode mounted adjacent said aperture,

said first, second, and third electrodes being selectively energizable to provide an electrical discharge through either or both of the labyrinthine discharge channels.

2. The rect-angular fiuorescent panel lamp of claim 1 in which the aperture in said partition plate is located adjacent a corner of said envelope.

3. The round fiuoresc-ent panel lamp of claim 1 in which said first and and said second vitreous plates and said partition plate are of annular shape and sealed together along their inner and outer margins.

4. A rectangular fluorescent panel lamp for producing multiple illumination levels comprising:

(a) an envelope formed by a first vitreous plate and a second vitreous plate,

(b) a partition plate coextensive with and interposed between said first and said second vitreous plates and having an aperture formed therein, said first and said second vitreous plates and said partition plate being sealed together along their margins,

(c) a plurality of parallel Walls extending from said first and said second vitreous plates and abutting .said partition plate to form labyrinthine discharge channels on either side of said partition plate cornprising a plurality of parallel channels joined at alternate ends,

(d) a rst electrode mounted in one of the labyrinthine channels in a region remote from said aperture,

(e) a second electrode mounted in the other labyrinthine channel in a region remote from said aperture, and (f) a third el-ectrode mounted adjacent said aperture,

said rst, second, and third electrodes being selectively energizable to provide an electrical discharge through either or both of the labyrinthine discharge channels. 5. -A round fluorescent panel lamp for producing multiple illumination levels comprising:

(a) an envelope formed by a first circul-ar vitreous plate and a second circular vitreous plate,

(b) a partition plate coextensive with and interposed between said first and s-aid second vitreous pl-ates and having an aperture formed therein, said first and said second vitreous plates and said partition plate being sealed together along their m-argins,

(c) a plurality of concentric and radial walls extending from said first and said second vitreous plates and abutting said partition plate to form labyrinthine discharge channels on either side of said partition plate,

(d) a first elect-rode mounted in one of the labyrinthine channels in a region remote from said aperture,

(e) a second electrode mounted in the other l-abyrinthine discharge channel in -a region remote from said aperture, and

(f) a third electrode mounted adjacent said aperture,

said first, second, and third electrodes being selectively energizable to provide an electric-al discharge through either or both of the labyrinthine discharge channels.

References Cited by the Examiner UNITED STATES PATENTS 1,974,888 9/1934 -Barclay 313-220 X 1,984,215 l\2/l934 Hatchner 313--220 X 2,465,123 3/1949 -Ruf et al. 313-204 X 3,047,763 7/ 119162; 'Inman 313--220 X 25 GEORGE N. WEST-BY, Primary Examiner.

C, R. CAMPBELL, Assistant Examiner. 

1. A FLUORSCENT PANEL LAMP FOR PRODUCING MULTIPLE ILLUMINATION LEVELS COMPRISING: (A) AN ENVELOPE FORMED BY A FIRST VITREOUS PLATE AND A SECOND VITREOUS PLATE, (B) A PARTITION PLATE COEXTENSIVE WITH AND INTERPOSED BETWEEN SAID FIRST AND SAID SECOND VITREOUS PLATES AND HAVING AN APERTURE FORMED THEREIN, SAID FIRST AND SAID SECOND VITREOUS PLATES AND SAID PARTITION PLATE BEING SEALED TOGETHER ALONG THEIR MARGINS, (C) A PLURALITY OF VITREOUS WALLS EXTENDING FROM SAID FIRST AND SAID SECOND VITREOUS PLATES AND ABUTTING SAID PARTITION PLATE TO FORM LAYBRINTHINE DISCHARGE CHANNELS WITHIN SAID ENVELOPE ON EITHER SIDE OF SAID PARTITION PLATE, (D) A FIRST ELECTRODE MOUNTED IN ONE OF THE LABYRINTHINE DISCHARGE CHANNELS IN A REGION REMOTE FROM SAID APERTURE, (E) A SECOND ELECTRODE MOUNTED IN THE OTHER LABYRINTHINE DISCHARGE CHANNEL IN A REGION REMOTE FROM SAID APERTURE, AND (F) A THIRD ELECTRODE MOUNTED ADJACENT SAID APERTURE, SAID FIRST, SECOND, AND THIRD ELECTRODES BEING SELECTIVELY ENERGIZABLE TO PROVIDE AN ELECTRICAL DISCHARGE THROUGH EITHER OR BOTH OF THE LABYRINTHINE DISCHARGE CHANNELS. 